As Mono Lake is of volcanic origin and formed around 760,000 years ago (per Wikipedia) I'd be astonished if the arsenophile(?) evolved there in that short a time span. Which leaves open the question of where it came from, and whether arsenic tolerance is present but dormant in other extremophiles.
Other points of note: never mind the cellular DNA integrating arsenate, the whole respiration cycle seems to be affected, presumably running on ATA rather than ATP. Which implies huge amounts of molecular booty in the shape of enzymes that are powered by a different reduction gradient (ATA-AMA rather than ATP-AMP).
Possible down to earth applications? Lest we forget, Pakistan has a monstrous problem with arsenic-contaminated wells ( http://www.irc.nl/page/16331 ) and a bacterial culture that thrives on arsenic could offer new approaches to arsenic sequestration. And that's just off the top of my head. (My biochemistry is, alas, too rusty to go much further without a refresher course. Hmm ...)
Do you have any basis for the claim the 760k years would not be enough time for such a feature to arise? After all, some surprisingly complicated things (http://en.wikipedia.org/wiki/Evolution_of_the_eye) are believed to have evolved (more than once) over shorter periods.
I just wanted to reiterate my suggestion for any bio-geeks living in the Bay Area - Mono Lake is only 2hrs drive from Bay Area and it is FASCINATING.
I would really encourage anyone who is interested in ecology and biochemistry to go check it out if you are passing through to Mammouth Lakes for snowboarding or taking a trip to Yosemite which is next door.
BTW, the ATP-AMP reaction is not a electrochemical reduction reaction, it's rather the mundane hydrolysis of a phosphodiester bond. We don't know what the energy potential of an arsenodiester bond is (although some speculation is that it carries a bit less energy).
I'd use the word arsenotolerant instead. The cells still preferentially utilize phosphorous when given the option. The prefix phile generally implies that they require such conditions to live, like a thermophile isn't viable at a temperature below (roughly) 40 C. This organism would have no trouble growing in the absence of Arsenic. =)
OK, this news is very interesting, but it does not prove much about extraterrestrial life.
We know that organisms can adapt to their environment. Incorporating some fraction of arsenic into a cell's dna is an example of such adaptation.
The question that really matters is "has life originated more than once in the universe?" This experiment has no bearing on that: They took a standard terrestrial cell, with a carbon-based history, and simply subjected it to some new conditions. This is NOT a new life form that originated from a novel environment and using a different chemistry. However, NASA is getting awfully close to selling it as such in their press conference, which is misleading.
if you're watching the press conference, they're very adamant that it doesn't prove anything about extraterrestrial life and they aren't able to yet say if life evolved with the arsenic or if it adapted.
but they're pointing out that it does show that forms of life different from our current definitions can exist and therefore the possibility of extraterrestrial life in non-earthlike environments exist.
Huh! Biochemistry major here... So I guess that the bacteria just rarely uses Sulphur-Sulphur (thiol) bonds in it's proteins, since Arsenic has a high affinity for it (and that's what causes arsenic toxicity in everything else).
http://en.wikipedia.org/wiki/Arsenic#Biochemical_basis_of_ar...
"suggesting the possibility of a biochemistry very different from the one we know"
Seems like a bit of an exaggeration, but news will be news. Thiols are important for the structure & enzymatic activity, but this bacteria is proof that there are ways around it. Besides that difference, I'm guessing they're the same.
Yes, beside the fact that they found a way to change the structure of their DNA, RNA, and a few hundreds enzymes involved in energy metabolism they are the same...
This is so huge that my money go into a mistake: I bet these bacteria just found a way to either get rid of arsenic or to neutralize its allosteric toxicity by maskerading or something. The paper is not out yet so I cannot give my opinon on the experimental data but from what I read there is no evidence that DNA actually contains arsenic and until that arrives I believe it's a red herring.
I'm sure DNA physical structure (angles, bends, etc.) with Arsenic instead of Phosphorous won't be exactly same. Arsenic has same tetrahedral structure as Phosphorous but the atom is sure bigger in size and at DNA scales, size would play a large role in determining shape of molecule. I'm sure you realize that physical interactions play a great role in a cell.
high resolution Mass spec is such a shitty technique and is completely non-quantitative. How do you know that arsenic isn't associated with, say, a protein that makes the DNA resistant to being taken apart chemically. I will believe this result when they stain the DNA and run samples of the DNA down a density gradient ultracentrifugation and show that arsenic content in the media correlates with increased density of DNA, as you would expect if the arsenic is replacing phosphorus. If you don't know what i'm talking about, it's this classical experiment:
Here is my personal scientific experience speaking: If you see it everywhere, then it's likely to be an artefact. Clean up your technique, clean your instruments, and go back to an old school technique. Remember how the physicists who discovered CMB cleaned out the pigeon scat from their microwave horn telescope before they started to believe what they saw.
"The researchers isolated the organism and found that when cultured in arsenate solution it grew 60% as fast as it did in phosphate solution — not as well, but still robustly. The culture did not grow at all when deprived of both arsenate and phosphate."
I don't know. You would think, but you can autoclave a solution of "deionized ultrafiltered water" which should have "no" carbon in it at all, and bacteria will find a way to grow in it if you get it contaminated, they will concentrate the trace trace trace amounts of carbon.
How carefully did they prep their DNA? These days nobody is careful and they use these crap kits which are good enough, convenient enough to get molecular biology done. The other day in lab I suggested someone isolate DNA using caesium chloride gradient ultracentifugation and the only people who knew what I was talking about were the two old (70+) year old senior scientists but they agreed that it was the way to go.
The lead author gives a talk at 2:26 in Part 1 that I thought was an excellent example of how to communicate science (or other technical subject) and implications to a general audience.
Perhaps NASA should be more cautious about holding a press on astrobiology, and with a Science embargo. Clearly everyone will immediately think of aliens, and for good reason. It's NASA, it's about astrobiology, and it's something big enough to embargo Science. They're just asking for all the alien stories. And let's be clear, these are not aliens.
Holding a press conference for this pretty sweet discovery was completely justified. The language in the press release made it clear ahead of time that Nasa didn’t make any discovery related to life on other worlds, only a few overly eager bloggers spun crazy theories like that.
Whoever is disappointed by this and claims that Nasa hyped too much doesn’t have her or his head screwed on right.
We not only could have a common ancestor, it seems to me to be almost certain. What are the chances that some other life has evolved with DNA completely independently
This seems silly. Phosphorous not being required for life seems obvious to me: ok, maybe it's believed to be used in all Earth-originated, carbon-based life, but why would we believe a priori that it's an absolutely necessary component of any biological life anywhere (which seems to be what's implied by NASA and the relation of this to exobiology)? If we develop silicon-based artificial intelligence (how do you define life, anyway? That matters when you're talking about astrobiology), would we run a headline, "Researchers prove carbon not required for life"?
I've always thought the scientific community stated that alien life may use a totally different biochemistry from us?
Edit: so, in some senses this is like P!=NP being proven, except less important, since it's only one component (phosphorus). It's scientifically a big deal but doesn't change the world because it's largely what we've always expected (the metaphor breaks down that this doesn't have the major secondary consequences like N=NP would).
> Phosphorous not being required for life seems obvious to me
It hasn't been noticed or proved, and conclusions drawn from actual science have a tendency to disprove common sense once in a while, which makes any actual discovery worthwhile.
Suppose Monopoles were discovered. Nothing really rules out their existence, Gauss's Law for magnetism is just an assertion that we've never seen a monopole, it's possible to patch up maxwell's equations to get monopoles. To some people, the existence of monopoles is 'obvious'.
It would still be a very big deal if monopoles were to be discovered, even in trace amounts, and no feasible way to make more of them.
Speaking without any domain knowledge, I think it has to do with "what can support the complexity required for life?". I would think it requires molecules that can do interesting things while at the same time survive their environment long enough to do those things.
I think the first artificial, human directed production of antimatter was by CERN in 1995. I'm not sure what you mean by "two weeks ago", but antimatter has been around a lot longer than that.
Why people constantly stick to the idea that all possible organisms must have similar biochemistry to us is beyond me.
Think about it: Out of the humongous search space of chemicals, the ones we use happened to work for us. A combination of randomness and building on what worked before got us to where we are. Why should life not be able to use chemistry in completely different ways in order to replicate itself? Why are we so arrogant as to think that our design is the only design?
Edit: My point is that our ratio of "shit we know" to "shit we don't know we don't know" is infinitesimally small in the field of possible lifeforms' biochemistry. That is, we only know stuff very close to us on a cosmic scale; we effectively have blinders to all other possibilities. And there's already a lot of biochemical variation on Earth: To give some small examples, viruses don't even have DNA, and plants use less amino acids than animals.
The self-similarity of what we have so far can be explained, I think, by evolution. We all started out from the same point, so there's very little incentive to "reinvent the wheel" as it were. Only under extreme conditions like we have here, or the geothermal vents underwater, do we observe marked differences.
> Why are we so arrogant as to think that our design is the only design?
We're not. Nobody is. The reason scientists don't look for life on other planets that is made of other chemicals is that we may not be able to recognize that as life. It's much better - read, scientific - to look for something we can recognize.
Also, there are chemical properties of the elements that make up life on Earth that allow for fast reactions, bonding, etc. Most of the rest of the elements in the periodic table react more slowly in normal conditions, making the process for life less likely. Not impossible. Just less likely. We think.
So we focus on looking for what we know about. That's the best way to do it. Nobody worth their degree will ever claim that our "design" (bad word choice, by the way) is the only one.
I agree with you that other life structures seem quite possible. I don't see the problem. But I'm not a professional biologists.
Still, it seems there are a number of biochemists who believe (or believed) that the structure of earth life could be unique. These people knew a lot more than me. So I wouldn't credit this to arrogance so much as a very complex question, one that doesn't necessarily get easier to solve the most data you get (at least on our scale of data).
I don't think it explictly comes down to such hubris. Certainly there are a lot of biases in this subject just like there are in any other ("rap isn't music," for instance), and human history is rife with analyzing the world in terms of the analyzer's perspective, the very definition of bias.
While replacing nitrogen in the air with, oh, sulfur, would likely have resulted in life forms (so the story goes) with an entirely different chain of evolutionary reactions and mutations, resulting in different body chemistry, yadda yadda yadda.
I do think it's news when we find out what one of these parallel evolutions might consist of. I mean, I'm not even sure sulfur-air would be a gas, so it's one thing to guess and speculate (fun), it's quite another to be able to say, in scientific fashion, "OK, what else is possible on this arsenic branch?" Said another way: there are a lot of grant proposals being written right now to finance exploration of this new territory. Hey, it beats paying for research into animals who produce petrochemicals as blood.
Who are people in this case? Most people don’t at all know what kind of life is plausible and not and they don’t care. I’m certain, however, that many biologists had an opinion on this prior to the discovery and I’m not really sure whether they thought that it was unlikely. For all we know most biologists expected this or a similar discovery, they just couldn’t yet assume it to be true because there wasn’t any evidence. Until now.
I think you might have confused unwillingness to talk about things we don't know with unwillingness to admit the possibility of things we don't know. Having some knowledge in common helps make conversations interesting. When two people talk about a possibility that's in the head of one of the participants, the conversation is unlikely to be on equal footing.
[+] [-] cstross|15 years ago|reply
Other points of note: never mind the cellular DNA integrating arsenate, the whole respiration cycle seems to be affected, presumably running on ATA rather than ATP. Which implies huge amounts of molecular booty in the shape of enzymes that are powered by a different reduction gradient (ATA-AMA rather than ATP-AMP).
Possible down to earth applications? Lest we forget, Pakistan has a monstrous problem with arsenic-contaminated wells ( http://www.irc.nl/page/16331 ) and a bacterial culture that thrives on arsenic could offer new approaches to arsenic sequestration. And that's just off the top of my head. (My biochemistry is, alas, too rusty to go much further without a refresher course. Hmm ...)
[+] [-] hyperbovine|15 years ago|reply
[+] [-] dotBen|15 years ago|reply
I just wanted to reiterate my suggestion for any bio-geeks living in the Bay Area - Mono Lake is only 2hrs drive from Bay Area and it is FASCINATING.
I would really encourage anyone who is interested in ecology and biochemistry to go check it out if you are passing through to Mammouth Lakes for snowboarding or taking a trip to Yosemite which is next door.
[+] [-] jacquesm|15 years ago|reply
You'd have to add another pass to get rid of the bacterial residue (possibly easier, but still).
[+] [-] dnautics|15 years ago|reply
Why not?
http://en.wikipedia.org/wiki/Berkeley_Pit#Extremophiles
BTW, the ATP-AMP reaction is not a electrochemical reduction reaction, it's rather the mundane hydrolysis of a phosphodiester bond. We don't know what the energy potential of an arsenodiester bond is (although some speculation is that it carries a bit less energy).
[+] [-] cKeyser|15 years ago|reply
[+] [-] drcode|15 years ago|reply
We know that organisms can adapt to their environment. Incorporating some fraction of arsenic into a cell's dna is an example of such adaptation.
The question that really matters is "has life originated more than once in the universe?" This experiment has no bearing on that: They took a standard terrestrial cell, with a carbon-based history, and simply subjected it to some new conditions. This is NOT a new life form that originated from a novel environment and using a different chemistry. However, NASA is getting awfully close to selling it as such in their press conference, which is misleading.
[+] [-] noodle|15 years ago|reply
but they're pointing out that it does show that forms of life different from our current definitions can exist and therefore the possibility of extraterrestrial life in non-earthlike environments exist.
[+] [-] jpwagner|15 years ago|reply
Of course it does not answer ALL of our questions, but it proves DNA does not need phosphorus! AMAZING!
[+] [-] civilian|15 years ago|reply
"suggesting the possibility of a biochemistry very different from the one we know" Seems like a bit of an exaggeration, but news will be news. Thiols are important for the structure & enzymatic activity, but this bacteria is proof that there are ways around it. Besides that difference, I'm guessing they're the same.
[+] [-] jaysonelliot|15 years ago|reply
Cynicism is cool and all that, but this sure sounds like big news to me.
[+] [-] crocowhile|15 years ago|reply
This is so huge that my money go into a mistake: I bet these bacteria just found a way to either get rid of arsenic or to neutralize its allosteric toxicity by maskerading or something. The paper is not out yet so I cannot give my opinon on the experimental data but from what I read there is no evidence that DNA actually contains arsenic and until that arrives I believe it's a red herring.
[+] [-] paraschopra|15 years ago|reply
[+] [-] dnautics|15 years ago|reply
http://en.wikipedia.org/wiki/Semiconservative_replication#Bi...
Here is my personal scientific experience speaking: If you see it everywhere, then it's likely to be an artefact. Clean up your technique, clean your instruments, and go back to an old school technique. Remember how the physicists who discovered CMB cleaned out the pigeon scat from their microwave horn telescope before they started to believe what they saw.
[+] [-] sorbus|15 years ago|reply
[+] [-] jaysonelliot|15 years ago|reply
Talk about a life-changing discovery!
[+] [-] spot|15 years ago|reply
[+] [-] stavrianos|15 years ago|reply
http://www.leevalley.com/newsletters/woodworking/2/3/article...
[+] [-] anigbrowl|15 years ago|reply
[+] [-] dnautics|15 years ago|reply
How carefully did they prep their DNA? These days nobody is careful and they use these crap kits which are good enough, convenient enough to get molecular biology done. The other day in lab I suggested someone isolate DNA using caesium chloride gradient ultracentifugation and the only people who knew what I was talking about were the two old (70+) year old senior scientists but they agreed that it was the way to go.
[+] [-] bld|15 years ago|reply
The lead author gives a talk at 2:26 in Part 1 that I thought was an excellent example of how to communicate science (or other technical subject) and implications to a general audience.
[+] [-] roadnottaken|15 years ago|reply
[+] [-] joelburget|15 years ago|reply
[+] [-] ugh|15 years ago|reply
Whoever is disappointed by this and claims that Nasa hyped too much doesn’t have her or his head screwed on right.
[+] [-] olalonde|15 years ago|reply
[1] http://en.wikipedia.org/wiki/Abiogenesis#Other_models
[+] [-] joelburget|15 years ago|reply
[+] [-] frisco|15 years ago|reply
I've always thought the scientific community stated that alien life may use a totally different biochemistry from us?
Edit: so, in some senses this is like P!=NP being proven, except less important, since it's only one component (phosphorus). It's scientifically a big deal but doesn't change the world because it's largely what we've always expected (the metaphor breaks down that this doesn't have the major secondary consequences like N=NP would).
[+] [-] bad_user|15 years ago|reply
It hasn't been noticed or proved, and conclusions drawn from actual science have a tendency to disprove common sense once in a while, which makes any actual discovery worthwhile.
[+] [-] davidsiems|15 years ago|reply
[+] [-] archgoon|15 years ago|reply
It would still be a very big deal if monopoles were to be discovered, even in trace amounts, and no feasible way to make more of them.
[+] [-] flogic|15 years ago|reply
[+] [-] InclinedPlane|15 years ago|reply
[+] [-] akharris|15 years ago|reply
This week: life without phosphorous.
Next week: flying skateboards?
[+] [-] prawn|15 years ago|reply
http://www.blogcdn.com/www.engadget.com/media/2010/01/parrot...
Risky, but I'd try it!
[+] [-] cryptoz|15 years ago|reply
[+] [-] gort|15 years ago|reply
http://www.sciencemag.org/content/early/2010/12/01/science.1...
[+] [-] vibragiel|15 years ago|reply
http://scienceblogs.com/pharyngula/2010/12/its_not_an_arseni...
[+] [-] bradfordw|15 years ago|reply
[+] [-] cryptoz|15 years ago|reply
[+] [-] TheSOB88|15 years ago|reply
Think about it: Out of the humongous search space of chemicals, the ones we use happened to work for us. A combination of randomness and building on what worked before got us to where we are. Why should life not be able to use chemistry in completely different ways in order to replicate itself? Why are we so arrogant as to think that our design is the only design?
Edit: My point is that our ratio of "shit we know" to "shit we don't know we don't know" is infinitesimally small in the field of possible lifeforms' biochemistry. That is, we only know stuff very close to us on a cosmic scale; we effectively have blinders to all other possibilities. And there's already a lot of biochemical variation on Earth: To give some small examples, viruses don't even have DNA, and plants use less amino acids than animals.
The self-similarity of what we have so far can be explained, I think, by evolution. We all started out from the same point, so there's very little incentive to "reinvent the wheel" as it were. Only under extreme conditions like we have here, or the geothermal vents underwater, do we observe marked differences.
[+] [-] cryptoz|15 years ago|reply
We're not. Nobody is. The reason scientists don't look for life on other planets that is made of other chemicals is that we may not be able to recognize that as life. It's much better - read, scientific - to look for something we can recognize.
Also, there are chemical properties of the elements that make up life on Earth that allow for fast reactions, bonding, etc. Most of the rest of the elements in the periodic table react more slowly in normal conditions, making the process for life less likely. Not impossible. Just less likely. We think.
So we focus on looking for what we know about. That's the best way to do it. Nobody worth their degree will ever claim that our "design" (bad word choice, by the way) is the only one.
[+] [-] joe_the_user|15 years ago|reply
Still, it seems there are a number of biochemists who believe (or believed) that the structure of earth life could be unique. These people knew a lot more than me. So I wouldn't credit this to arrogance so much as a very complex question, one that doesn't necessarily get easier to solve the most data you get (at least on our scale of data).
[+] [-] rhizome|15 years ago|reply
While replacing nitrogen in the air with, oh, sulfur, would likely have resulted in life forms (so the story goes) with an entirely different chain of evolutionary reactions and mutations, resulting in different body chemistry, yadda yadda yadda.
I do think it's news when we find out what one of these parallel evolutions might consist of. I mean, I'm not even sure sulfur-air would be a gas, so it's one thing to guess and speculate (fun), it's quite another to be able to say, in scientific fashion, "OK, what else is possible on this arsenic branch?" Said another way: there are a lot of grant proposals being written right now to finance exploration of this new territory. Hey, it beats paying for research into animals who produce petrochemicals as blood.
[+] [-] ugh|15 years ago|reply
[+] [-] benatkin|15 years ago|reply
[+] [-] RiderOfGiraffes|15 years ago|reply
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[+] [-] RiderOfGiraffes|15 years ago|reply
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